This is a list of noted biologists.
- Humayun Abdulali (1914–2001), Indian ornithologist
- Aziz Ab'Saber (1924–2012), Brazilian geographer, geologist and ecologist
- Erik Acharius (1757–1819), Swedish botanist
- Johann Friedrich Adam (18th century–1806), Russian botanist
- Arthur Adams (1820–1878), English physician and naturalist
- Henry Adams (1813–1877), English naturalist and conchologist
- William Adamson (1731–1793), Scottish botanist (abbr. in botany: Aiton)
- Michel Adanson (1727–1806), French naturalist (abbr. in botany: Adans.)
- Monique Adolphe (born 1932), French cell biologist
- Edgar Douglas Adrian (1889–1977), British electrophysiologist, winner of the 1932 Nobel Prize in Physiology or Medicine for his research on neurons
- Adam Afzelius (1750–1837), Swedish botanist
- Carl Adolph Agardh (1785–1859), Swedish botanist
- Jacob Georg Agardh (1813–1901), Swedish botanist
- Louis Agassiz (1807–1873), Swiss zoologist
- Alexander Agassiz (1835–1910), American zoologist, son of Louis Agassiz
- Nikolaus Ager (1568–1634), French botanist
- Pedro Alberch i Vié (1954–1998), Spanish naturalist
- Bruce Alberts (born 1938), American biochemist, former President of the United States National Academy of Sciences
- Nora Lilian Alcock (1874–1972), British pioneer in plant pathology
- Boyd Alexander (1873–1910), English ornithologist
- Horace Alexander (1889–1989), English ornithologist
- Richard D. Alexander (born 1930), American evolutionary biologist
- Wilfred Backhouse Alexander (1885–1965), English ornithologist
- Alfred William Alcock (1859–1933), British naturalist
- Salim Ali (1896–1987), Indian ornithologist
- Frédéric-Louis Allamand (1736–after 1803), Swiss botanist (abbr. in botany: F.Allam.)
- Warder Clyde Allee (1885–1955), American zoologist and ecologist, identified the Allee effect
- Joel Asaph Allen (1838–1921), American; birds, mammals
- George James Allman (1812–1898), British naturalist
- June Dalziel Almeida (1930–2007), Scottish virologist
- Tikvah Alper (1909–1995), South African radiobiologist
- Prospero Alpini (1553–1617), Italian botanist
- Sidney Altman (born 1939), Canadian-born molecular biologist, winner of the 1989 Nobel Prize in Chemistry for his work on RNA
- Bruce Ames (born 1928), American biochemist, inventor of the Ames test
- José Alberto de Oliveira Anchieta (1832–1897), Portuguese naturalist
- George French Angas (1822–1886), English explorer, naturalist, conchologist and painter
- Mary Arlene Appelhof (1936–2005), American biologist
- Jakob Johan Adolf Appellöf (1857–1921), Swedish marine zoologist
- Agnes Robertson Arber (1879–1960), British plant morphologist and anatomist, historian of botany and philosopher of biology
- Aristotle (384 BC–322 BC), Greek philosopher
- Emily Arnesen (1867–1928), Norwegian zoologist
- Ruth Arnon (born 1933), Israeli biochemist
- Peter Artedi (1705–1735), Swedish naturalist
- Gilbert Ashwell (1916–2014), American biochemist, pioneer in the study of cell receptor
- Ana Aslan (1897–1988), Romanian biologist
- Jean Baptiste Audebert (1759–1800), French naturalist
- Jean Victoire Audouin (1797–1841), French zoologist
- John James Audubon (1786–1851), American ornithologist
- Charlotte Auerbach (1899–1994), German geneticist, founded the discipline of mutagenesis
- Linda Avey (born 1960), American biologist
- Richard Axel (born 1946), Nobel Prize–winning physiologist
- Julius Axelrod (1912–2004), American biochemist, winner of the 1970 Nobel Prize in Physiology or Medicine for his research on catecholamine neurotransmitters
- William Orville Ayres (1817–1887), American physician and ichthyologist
- Félix de Azara (1746–1811), Spanish naturalist
Ba-Bi
- Churchill Babington (1821–1889), British archaeologist and conchologist
- John Bachman (1790–1874), American naturalist
- Curt Backeberg (1894–1966), German botanist (abbr. in botany: Backeb.)
- Karl Ernst von Baer (1792–1876), embryologist
- Liberty Hyde Bailey (1858–1954), American botanist (abbr. in botany: L.H.Bailey)
- Spencer Fullerton Baird (1823–1887), birds and mammals
- Scott Baker (born 1954), American marine biologist
- John Hutton Balfour (1808–1884), Scottish botanist (abbr. in botany: Balf.)
- David Baltimore (born 1938), Nobel Prize in Physiology or Medicine 1975
- Outram Bangs (1863–1932), American zoologist
- Joseph Banks (1743–1820), biologist, botanist (abbr. in botany: Banks)
- Robert Bárány (1876–1936), Austrian physician, received the 1914 Nobel Prize in Physiology or Medicine for his research on the vestibular system
- Ben Barres (born 1955), American neurobiologist
- Benjamin Smith Barton (1766–1815), American botanist (abbr. in botany: Barton)
- John Bartram (1699–1777), American botanist (abbr. in botany: Bartram)
- William Bartram (1739–1823), American naturalist (abbr. in botany: W.Bartram)
- Anton de Bary (1831–1888), contribution: studies of plant diseases
- Henry Walter Bates (1825–1892), English naturalist
- Patrick Bateson (born 1938), English biologist and science writer, President of the Zoological Society of London
- August Johann Georg Karl Batsch (1762–1802), German botanist, mycologist
- Nicolas Baudin (1754–1803), French botanist
- Gaspard Bauhin (1560–1624), Swiss botanist, introduced binomial nomenclature into taxonomy, which was used by Linnaeus (abbr. in botany: C.Bauhin)
- Johann Matthäus Bechstein (1757–1822), German naturalist (abbr. in botany: Bechst.)
- Rollo Beck (1870–1950), American ornithologist
- Charles William Beebe (1877–1962), biologist
- Martinus Beijerinck (1851–1931), Dutch microbiologist and botanist, discovered viruses
- Thomas Bell (1792–1880), English naturalist
- David Bellamy (born 1933), English botanist
- Edward Turner Bennett (1797–1836), English zoologist
- George Bentham (1800–1884), English botanist (abbr. in botany: Benth.)
- Robert Bentley (1821–1893), English botanist (abbr. in botany: Bentley)
- Jacques Benveniste (1935–2004), French immunologist
- Wilson Teixeira Beraldo (1917–1998), Brazilian physician and physiologist, codiscoverer of bradykinin
- Hans Berger (1873–1941), German neuroscientist, one of the founders of electroencephalography
- Carl Bergmann (1814–1865), German anatomist, physiologist and biologist who developed the Bergmann's rule
- Rudolph Bergh (1824–1909), Danish physician and zoologist
- Claude Bernard (1813–1878), French physiologist and father of the concept of homeostasis
- Samuel Stillman Berry (1887–1984), American marine zoologist
- Thomas Bewick (1753–1828), English ornithologist
- Colin Bibby (1948–2004), English ornithologist
- Gabriel Bibron (1806–1848), French zoologist
- Johannes Abraham Bierens de Haan (1883–1953), Dutch biologist and ethologist
- Ann Bishop (1899–1990), English biologist
- Biswamoy Biswas (1923–1994), Indian ornithologist
Bl-Bu
- Liz Blackburn (born 1948), Australian/US Nobel Prize–winning researcher in the field of telomeres and the "telomerase" enzyme
- John Blackwall (1790–1881), British entomologist
- Henri Marie Ducrotay de Blainville (1777–1850), French zoologist
- Albert Francis Blakeslee (1874–1954), American botanist, best known for research on Jimsonweed and the sexuality of fungi
- Thomas Blakiston (1832–1891), English naturalist
- William Thomas Blanford (1832–1905), English naturalist
- Pieter Bleeker (1819–1878), Dutch ichthyologist
- Günter Blobel (born 1936), German Nobel Prize-winning biologist who discovered that newly synthesized proteins contain "address tags" which direct them to the proper location within the cell.
- Steven Block (born 1952), American biophysicist who measured the mechanical properties of single bio-molecules
- Carl Ludwig Blume (1789–1862), German-Dutch botanist (abbr. in botany: Blume)
- Johann Friedrich Blumenbach (1752–1840), German physiologist and anthropologist
- Edward Blyth (1810–1873), English zoologist
- José Vicente Barbosa du Bocage (1823–1907), Portuguese zoologist
- Pieter Boddaert (1730–1795 or 1796), naturalist
- Charles Lucien Bonaparte (1803–1857), French naturalist
- James Bond (1900–1989), American ornithologist
- Franco Andrea Bonelli (1784–1830), Italian ornithologist
- August Gustav Heinrich von Bongard (1786–1839), German botanist
- John Tyler Bonner (1920-2019), American developmental biologist
- Charles Bonnet (1720–1793), Swiss naturalist
- Aimé Bonpland (1773–1858), French botanist (abbr. in botany: Bonpl.)
- Jules Bordet (1870–1961), Belgian immunologist and microbiologist, winner of the 1919 Nobel Prize in Physiology or Medicine for his discovery of the complement system in the immune system
- Antonina Georgievna Borissova (1903–1970), Russian botanist
- Norman Borlaug (born 1914), American agricultural scientist, humanitarian, Nobel laureate, and the father of the Green Revolution
- Louis Augustin Guillaume Bosc (1759–1828), French zoologist
- George Albert Boulenger (1858–1937), Belgian zoologist
- Jules Bourcier (1797–1873), French naturalist
- Margaret Bradshaw New Zealand Antarctic researcher, paleontologist
- Johann Friedrich von Brandt (1802–1879), German naturalist (abbr. in botany: Brandt)
- Sara Branham Matthews (1888–1962), American microbiologist
- Christian Ludwig Brehm (1787–1864), German ornithologist
- Alfred Brehm (1829–1884), German zoologist
- Sydney Brenner (born 1927), British molecular biologist, winner of the 2002 Nobel Prize in Physiology or Medicine
- Thomas Mayo Brewer (1814–1880), American naturalist
- William Brewster (1851–1919), American ornithologist
- Mathurin Jacques Brisson (1723–1806), French zoologist
- Nathaniel Lord Britton (1859–1934), American botanist (abbr. in botany: Britton)
- Thomas D. Brock (born 1926), American biologist, discoverer of hyperthermophiles
- Adolphe Theodore Brongniart (1801–1876), French botanist (abbr. in botany: Brongn.)
- Robert Broom (1866–1951), South African paleontologist
- James H. Brown, American ecologist
- Robert Brown (1773–1858), botanist (abbr. in botany: R.Br.)
- David Bruce (1855–1931), Scottish pathologist and microbiologist
- Jean Guillaume Bruguière (1750–1798), French naturalist
- Morten Thrane Brünnich (1737–1827), Danish zoologist
- Francis Buchanan-Hamilton (1762–1829), Scottish zoologist and botanist
- Stephen L. Buchmann, co-author of The Forgotten Pollinators
- Linda B. Buck (born 1947), American physiologist and Nobel prize winner
- Samuel Botsford Buckley (1809–1884), American naturalist (abbr. in botany: Buckley)
- Buffon (1707–1788), French naturalist (abbr. in botany: Buffon)
- William Bullock (1773–1849), English naturalist
- Walter Buller (1838–1906), New Zealand naturalist
- James Bulwer (1794–1879), English naturalist and conchologist
- Alexander G. von Bunge (1803–1890), German-Russian zoologist
- Luther Burbank (1849–1926), American horticulturalist
- Hermann Burmeister (1807–1892), German zoologist
- Carolyn Burns New Zealand ecologist
- Carlos Bustamante (born 1951), American biophysicist, discovered "molecular tweezers" to manipulate DNA
- Ernesto Bustamante (born 1950), Peruvian biochemist, specialist in mitochondria. Currently works on DNA paternity testing
- Jean Cabanis (1816–1906), German ornithologist
- Ángel Cabrera (1879–1960), Spanish zoologist
- George Caley (1770–1829), Discovery of Mount Banks
- Rudolf Jakob Camerarius (1665–1721), German botanist
- Frederick Campion Steward (1904–1993), British botanist
- A. P. de Candolle (1778–1841), Swiss botanist
- Philip Pearsall Carpenter (1819–1877), conchologist
- Alexis Carrel (1873–1944), French biologist and surgeon, winner of the 1912 Nobel Prize in Physiology or Medicine for his work on sutures and organ transplants, advocate of eugenics
- Elie-Abel Carrière (1818–1896), French botanist
- Clodoveo Carrión Mora (1883–1957), Ecuadorian paleontologist and naturalist
- Sean B. Carroll, American evolutionary development biologist
- Rachel Carson (1907–1964), biologist, author of Silent Spring
- George Washington Carver (1860–1943), American botanist
- John Cassin (1813–1869), American ornithologist
- Alexandre de Cassini (1781–1832), French botanist (abbr. in botany: Cass.)
- Amy Castle (1880-1971), New Zealand entomologist
- William E. Castle (1867–1962), American geneticist
- Mark Catesby (1683–1749), English naturalist
- Andrea Cesalpino (1519–1603), Italian botanist
- Francesco Cetti (1726–1778), Italian zoologist
- Carlos Chagas (1879–1934), Brazilian physician
- Adelbert von Chamisso (1781–1838), German botanist
- Min Chueh Chang (1908–1991), biologist
- Ann Chapman (1937-2009), New Zealand limnologist
- Frank Michler Chapman (1864–1945), ornithologist
- Martha Chase (1927–2003), American biologist, conducted the Hershey-Chase experiment which linked DNA to heredity
- Thomas Frederic Cheeseman (1846–1923), New Zealand botanist and naturalist
- Robert Ernest Cheesman (1878–1962), English military officer, explorer and ornithologist
- Sergei Chetverikov (1880–1959), Russian population geneticist
- Charles Chilton (1860–1929), New Zealand zoologist
- Carl Chun (1852–1914), German marine biologist
- Nathan Cobb (1859–1932), American biologist, considered the founder of the discipline of nematology
- Leonard Cockayne (1855-1934), New Zealand botanist
- Alfred Cogniaux (1841–1916), Belgian botanist (abbr. in botany: Cogn.)
- Stanley Cohen (born 1922), American biologist, Nobel Prize Laureate in Physiology and Medicine (1986) for his discovery of growth factors.
- James J. Collins, American biologist, synthetic biology and systems biology pioneer
- Henry Boardman Conover (1892–1950), American ornithologist
- Timothy Abbott Conrad (1803–1877), American malacologist
- James Graham Cooper (1830–1902), American naturalist
- William Cooper (1798–1864), American conchologist
- Edward Drinker Cope (1840–1897), fish, reptiles, paleontology
- Charles Coquerel (1822–1867), French navy surgeon and entomologist
- Carl Ferdinand Cori (1896–1984), American biochemist, winner of the 1947 Nobel Prize in Physiology or Medicine for his work on the Cori cycle
- Gerty Cori (1886–1957), American biochemist, first American woman to win a Nobel Prize in science, the prize was awarded to her and her husband Carl for their work on the Cori cycle
- Charles B. Cory (1857–1921), American ornithologist
- Emanuel Mendez da Costa (1717–1791), English botanist, naturalist, philosopher
- Elliott Coues (1842–1899), American ornithologist
- Marjorie Courtenay-Latimer (1907–2004), South African zoologist
- Jacques Cousteau (1910–1997), French marine biologist and explorer
- Miguel Rolando Covian (1913–1992), Argentine-Brazilian neurophysiologist, father of Brazilian neurophysiology
- Frederick Vernon Coville (1867–1937), American botanist
- Robert K. Crane, (born 1919), American biochemist, discovered sodium-glucose cotransport
- Lucy Cranwell (1907-2000), New Zealand botanist
- Philipp Jakob Cretzschmar (1786–1845), German zoologist
- Francis Crick (1916–2004), one of the discoverers of the structure of the DNA molecule and a neurobiologist
- Joseph Charles Hippolyte Crosse (1826–1898), French conchologist
- Nicholas Culpeper (1616–1654), English botanist
- Allan Cunningham (1791–1839), English botanist
- G. H. Cunningham (1892-1962), New Zealand mycologist
- Kathleen Curtis (1892-1993), New Zealand mycologist and plant pathologist
- William Curtis (1746–1799), English botanist
- Georges Cuvier (1769–1832), French naturalist
- Valerie Daggett, American bioengineer
- Anders Dahl (1751–1789), namesake of the Dahlia
- William Healey Dall (1845–1927), malacologist, exploration of Alaska
- J. C. Daniel (1927–2011), Indian naturalist, director of the Bombay Natural History Society
- Charles Darwin (1809–1882), British naturalist, author and biologist
- Erasmus Darwin (1731–1802), doctor, naturalist, grandfather of Charles
- Charles Davenport (1866–1944), American biologist and eugenicist, founded the Eugenics Record Office at Cold Spring Harbor Laboratory
- Armand David (1826–1900), French zoologist and botanist
- Bernard Davis (1916–1994), American biologist
- Richard Dawkins (born 1941), British evolutionary biologist
- George Delahunty (born 1952), American physiologist, endocrinologist, and professor of biology at Goucher College
- Pierre Antoine Delalande (1787–1823), French naturalist
- Max Delbrück (1906–1981), German physicist and biologist known for work on the replication mechanism of viruses
- Richard Dell (1920–2002), New Zealand malacologist
- Stefano Delle Chiaje (1794–1860), Italian
- Paul Émile de Puydt (1810–1888), Belgian botanist
- René Louiche Desfontaines (1750–1833), French botanist
- Gérard Paul Deshayes (1795–1875), French geologist and conchologist.
- Anselme Gaëtan Desmarest (1784–1838), French zoologist
- Ernst Dieffenbach (1811–1855), German naturalist
- Johann Jacob Dillenius (1684–1747), German botanist
- Lewis Weston Dillwyn (1778–1855), British botanist and conchologist
- Joan Dingley (1916-2008), New Zealand mycologist
- Walter Dobrogosz (born 1933), American microbiologist, discoverer of Lactobacillus reuteri
- Theodosius Dobzhansky (1900–1975), American geneticist and evolutionary biologist
- Rembert Dodoens (1517–1585), Flemish botanist
- Anton Dohrn (1840–1909), German marine biologist
- David Don (1799–1841), British botanist
- James Donn (1758–1813), English botanist
- Jean Dorst (1924–2001), French ornithologist
- Henry Doubleday (1808–1875), British entomologist
- David Douglas (1799–1834), Scottish botanist
- Jonas C. Dryander (1748–1810), Swedish botanist
- Patricia Louise Dudley (1929–2004) American zoologist
- Félix Dujardin (1802–1860), biologist
- Renato Dulbecco (1914–2012), biologist
- Ronald Duman, Biological psychiatry
- André Marie Constant Duméril (1774–1860), French zoologist
- Michel Felix Dunal (1789–1856), French botanist
- Robin Dunbar (born 1947), Italian virologist
- Gerald Durrell (1925–1995), British naturalist
- Sylvia Earle (born 1935), American oceanographer
- John Carew Eccles (1903–1997), Australian neurophysiologist and winner of the 1963 Nobel Prize in Physiology or Medicine for his work on the synapse
- Christian Friedrich Ecklon (1795–1868), Danish botanist (abbr. in botany: Eckl.)
- Gerald Edelman (born 1929), Nobel Prize for immunology work, later work in neuroscience
- George Edwards (1693–1773), British naturalist
- Christian Gottfried Ehrenberg (1795–1876), German biologist and microscopist
- Paul Ehrlich (1854–1915), German Nobel Prize-winning immunologist
- Karl Eichwald (1795–1876), Russian geologist and physician
- Theodor Eimer (1843–1898), German zoologist
- George Eliava (1892–1937), Georgian microbiologist
- Daniel Giraud Elliot (1835–1915), American zoologist
- Günther Enderlein (1872–1968), German zoologist and entomologist
- Stephan Ladislaus Endlicher (1804–1849), Austrian botanist (abbr. in botany: Endl.)
- Michael S. Engel (born 1971), American paleontologist and entomologist
- George Engelmann (1809–1884), German-American botanist
- Adolf Engler (1844–1930), German botanist (abbr. in botany: Engl.)
- Johann Christian Polycarp Erxleben (1744–1777), German naturalist.
- Johann Friedrich von Eschscholtz (1793–1831), Baltic German biologist and explorer, namesake of the California poppy
- Constantin von Ettingshausen (1826–1897), Austrian botanist
- Warren Ewens, American mathematical population geneticist
- Thomas Campbell Eyton (1809–1880), English naturalist
- Jean Henri Fabre (1823–1915), French entomologist
- Johan Christian Fabricius (1745–1808), Danish entomologist
- David Fairchild (1869–1954), American botanist
- Hugh Falconer (1808–1865), Scottish paleontologist
- Filippo Farsetti (1703-1774), Venetian art collector and botanist
- Leonardo Fea (1852–1903), Italian zoologist
- Christoph Feldegg (1780–1845), Austrian naturalist
- Lewis J. Feldman (born 1945), American botanist
- Howard Barraclough (Barry) Fell (1917–1994), English zoologist and pre-Columbian contact theorist
- Sérgio Ferreira (born 1934), Brazilian pharmacologist
- Harold John Finlay (1901–1951), New Zealand palaeontologist and conchologist
- Otto Finsch (1839–1917), German naturalist
- Johann Fischer von Waldheim (1771–1853), German entomologist
- James Fisher (1922–1970), English ornithologist
- Paul Henri Fischer (1835–1893): French physician, zoologist, malacologist and paleontologist
- Ronald Fisher (1890–1962), British biologist and statistician, one of the founders of population genetics
- Leopold Fitzinger (1802–1884), Austrian zoologist
- Tim Flannery (born 1956) Australian biologist
- Jim Flegg, British ornithologist
- Alexander Fleming (1881–1955), British medical scientist
- Charles Fleming (1916-1987), New Zealand ornithologist, palaeontologist
- Walther Flemming (1843–1905), German physician and anatomist, discoverer of mitosis and chromosomes
- Thomas Bainbrigge Fletcher (1878–1950), English entomologist
- Howard Walter Florey (1898–1968), pharmacologist who was the co-inventor of penicillin
- Brian J. Ford (born 1939), British biologist and writer
- E. B. Ford (1901–1988), British ecological geneticist
- Margot Forde (1835-1995), New Zealand botanist
- Peter Forsskål (1732–1763), Swedish naturalist
- Georg Forster (1754–1794), German naturalist (abbr. in botany: G.Forst.)
- Peter Forster (geneticist) (born 1967), German geneticist
- Johann Reinhold Forster (1729–1798), German naturalist
- Robert Fortune (1813–1880), Scottish botanist
- Dian Fossey (1932–1985), American zoologist
- Rosalind Franklin (1920–1958), contributor to the discovery of the structure of DNA
- Francisco Freire Allemão e Cysneiro (1797–1874), Brazilian botanist
- Elias Magnus Fries (1794–1878), one of the founders of modern mushroom taxonomy
- Karl von Frisch (1886–1982), Austrian ethologist and Nobel laureate, best known for pioneering studies of bees
- Imre Frivaldszky (1799–1870), Hungarian botanist
- Leonhart Fuchs (1501–1566), German botanist
- José María de la Fuente Morales (1855–1932), Spanish biologist
- Louis Agassiz Fuertes (1874–1927), American ornithologist
- Joseph Gaertner (1732–1791), German botanist
- François Gagnepain (1866–1952), French botanist
- Joseph Paul Gaimard (1796–1858), French naturalist
- Biruté Galdikas (born 1946), Canadian primatologist, conducted pioneering studies on orangutans
- Robert Gallo (born 1937), American virologist and co-discoverer of HIV
- William Gambel (1823–1849), American naturalist
- Prosper Garnot (1794–1838), French naturalist
- Charles Gaudichaud-Beaupré (1789–1854), French botanist
- Michael Gazzaniga, American cognitive neuroscientist, best known for his research on split-brain patients
- Howard Scott Gentry (1903–1993), American botanist
- John Gerard (1545–1611/12), English botanist
- Conrad von Gesner (1516–1565), Swiss naturalist (abbr. in botany: Gesner)
- Luca Ghini (1490–1566), Italian botanist
- Clelia Giacobini (1931–2010), Italian microbiologist, a pioneer of microbiology applied to conservation-restoration
- John H. Gillespie, American molecular evolutionist and population geneticist
- Charles Henry Gimingham (born 1923), British botanist
- Charles Frédéric Girard (1822–1895), French biologist, ichthyologist, herpetologist
- Johann Friedrich Gmelin (1748–1804), German naturalist (abbr. in botany: J.F.Gmel.)
- Johann Georg Gmelin (1709–1755), German naturalist (abbr. in botany: J.G.Gmel.)
- Samuel Gottlieb Gmelin (1744–1774), German botanist (abbr. in botany: S.G.Gmel.)
- Frederick DuCane Godman (1834–1919), English naturalist and ornithologist
- Émil Goeldi (1859–1917), Swiss-Brazilian naturalist and zoologist
- Johann Wolfgang von Goethe (1749–1832), known for his literary works but also a scientist. In biology: his theory of plant metamorphosis stipulated that all plant formation stems from a modification of the Leaf.
- Camillo Golgi (1843–1926), Italian physician and Nobel prize winner, pioneer in neurobiology
- Jane Goodall (born 1934), British primatologist, ethologist and anthropologist, best known for conducting a forty-year study of chimpanzee social and family life.
- George Gordon (1806–1879), British botanist
- Philip Henry Gosse (1810–1888), English naturalist
- Augustus Addison Gould (1805–1866), American conchologist.
- John Gould (1804–1881), English ornithologist
- Stephen Jay Gould (1941–2002), American paleontologist
- Alfred Grandidier (1836–1921), French naturalist and explorer
- Guillaume Grandidier (1873–1957), French naturalist and explorer son of Alfred Grandidier
- Temple Grandin (born 1947), American animal scientist; world-renowned as a designer of humane livestock facilities and for her writings on her experience with autism
- Chapman Grant (1887–1983), American herpetologist
- Pierre-Paul Grassé (1895–1985), French zoologist
- Asa Gray (1810–1888), American botanist
- George Robert Gray (1808–1872), English zoologist
- J.E. Gray (1800–1875), British zoologist
- Andrew Jackson Grayson (1819–1869), American ornithologist
- William King Gregory (1876–1970), American zoologist
- Edward Grey, 1st Viscount Grey of Fallodon (1862–1933), British ornithologist
- Janet Grieve New Zealand biological oceanographer
- Frederick Griffith (1879–1941), British bacteriologist
- Jeremy Griffith (born 1945), Australian zoologist
- Jan Frederik Gronovius (1690–1762), Dutch botanist
- Pavel Grošelj (1883–1940), biologist and belletrist
- Colin Groves (1942–2017), Professor of biological anthropology in Australia
- Félix Édouard Guérin-Méneville (1799–1874), French entomologist
- Johann Anton Güldenstädt (1745–1781), German naturalist
- Allvar Gullstrand (1862–1930), Swedish ophthalmologist, winner of the 1911 Nobel Prize for Physiology or Medicine "for research on the image formation by the lens of the eye"
- Johann Ernst Gunnerus (1718–1773), Norwegian botanist
- Albert C. L. G. Günther (1830–1914), British/German zoologist
- Ernst Haeckel (1834–1919), German physician, zoologist and evolutionist
- Hermann August Hagen (1817–1893), German entomologist
- J. B. S. Haldane (1892–1964), British evolutionary biologist and co-founder of population genetics
- William Donald Hamilton (1936–2000), British evolutionary biologist
- Sylvanus Charles Thorp Hanley (1819–1899), British conchologist and malacologist
- Thomas Hardwicke (1755–1835), English naturalist
- Alister Clavering Hardy (1896–1985), English marine biologist and pioneer student of the biological basis of religion
- Richard Harlan (1796–1843), American naturalist, zoologist, physicist and paleontologist
- Denham Harman (born 1916), American biogerontologist, father of the free radical theory of aging
- David Harrison (1926–2015), English zoologist
- Maarten 't Hart (born 1944), Dutch biologist and writer
- Ernst Hartert (1859–1933), German ornithologist
- Gustav Hartlaub (1814–1900), German zoologist
- Karl Theodor Hartweg (1812–1871), German botanist
- William Henry Harvey (1811–1866), Irish phycologist
- Hans Hass (1919–2013), Austrian biologist
- Frederik Hasselquist (1722–1752), Swedish naturalist
- Arthur Hay, 9th Marquess of Tweeddale (1824–1878), English ornithologist
- James Hector (1834–1907), Scottish geologist, naturalist, and surgeon
- Charles Hedley (1862–1926), naturalist, active in Australia
- Oskar Heinroth (1871–1945), German biologist, a founder of ethology
- Edmund Heller (1875–1939), American zoologist
- Wilhelm Hemprich (1796–1825), German naturalist
- Willi Hennig (1913–1976) German biologist, founder of cladistics
- John Stevens Henslow (1796–1861), English mineralogist, botanist and clergyman
- Johann Hermann (1738–1800), French physician and naturalist
- Albert William Herre (1868–1962), American ichthyologist and lichenologist
- Alfred Hershey (1908–1997), American bacteriologist, winner of the 1969 Nobel Prize in Physiology or Medicine for his work on the genetics of viruses
- Philip Hershkovitz (1909–1997), American mammalogist noted especially as a primatologist
- Leo George Hertlein (1898–1972), American paleontologist and malacologist
- Archibald Vivian Hill (1886–1977), British physiologist, winner of the 1922 Nobel Prize in Physiology or Medicine for elucidation of mechanical work in muscles
- Brian Houghton Hodgson (1800–1894), English naturalist
- Jan van der Hoeven (1802–1868), Dutch zoologist
- Bruno Hofer (1861–1916), German fisheries scientist
- Johann Centurius Hoffmannsegg (1766–1849), German botanist, entomologist and ornithologist
- Jacques Bernard Hombron (1798–1852), French naturalist
- Leroy Hood (born 1939), American biochemist, developed high speed automated DNA sequencer
- Robert Hooke (1635–1703), British natural philosopher and Secretary to the Royal Society
- Joseph Dalton Hooker (1817–1911), British botanist, explorer and Director of Kew Botanic Gardens
- William Jackson Hooker (1785–1865), British botanist, Director of Kew Botanic Gardens
- John "Jack" Horner (born 1946), American paleontologist, specialized in dinosaurs
- Thomas Horsfield (1773–1859), American naturalist
- Bernardo Houssay (1887–1971), Argentine physiologist, winner of the 1947 Nobel Prize in Physiology or Medicine for the function of the pituitary hormones in regulating blood sugar (glucose) in animals.
- Martinus Houttuyn (1720–1798), Dutch naturalist
- Albert Howard (1873–1947), British botanist
- Henry Eliot Howard (1873–1940), English ornithologist
- Sarah Blaffer Hrdy (born 1946), U.S. anthropologist who made contributions to evolutionary psychology and sociobiology
- David H. Hubel (born 1926), Canadian-Born American neurobiologist, winner of the 1981 Nobel Prize in Physiology or Medicine for research on the visual system
- François Huber (1750–1831), Swiss naturalist
- Ambrosius Hubrecht (1853–1915), Dutch zoologist
- William Henry Hudson (1841–1922), Argentinian-British ornithologist
- Alexander von Humboldt (1769–1859), German naturalist and explorer
- Allan Octavian Hume (1829–1912), British ornithologist
- Rob Hume, British ornithologist
- George Evelyn Hutchinson (1903–1991), American ecologist and limnologist
- Frederick Wollaston Hutton (1835–1905), English biologist and geologist, later worked in New Zealand
- Julian Sorell Huxley (1887–1975), English zoologist and contributor to the modern evolutionary synthesis; first D-G of UNESCO
- Thomas Henry Huxley (1825–1895), English zoologist and advocate of evolution, agnosticism and scientific education
- Alpheus Hyatt (1838–1902), American neo-Lamarckian
- Libbie Hyman (1888–1969), invertebrate zoologist
- Josef Hyrtl (1810–1894), Austrian anatomist
- Hermann von Ihering (1850–1930), German naturalist
- Johann Karl Wilhelm Illiger (1775–1813), German entomologist
- Jan Ingenhousz (1730–1799), Dutch-born British botanist
- Tom Iredale (1880–1972), English conchologist and ornithologist
- Paul Erdmann Isert (1756–1789), German botanist
- François Jacob (born 1920), French biologist, Nobel laureate
- Nikolaus Joseph von Jacquin (1727–1817), Dutch-born Austrian botanist
- Honoré Jacquinot (1815–1887), French surgeon and zoologist
- Daniel H. Janzen (born 1939), American entomologist and ecologist
- William Jardine (1800–1874), Scottish naturalist
- Feliks Pawel Jarocki (1790–1865), Polish zoologist
- Thomas C. Jerdon (1811–1872), British zoologist and botanist
- Wilhelm Johannsen (1857–1927), (coined the term gene)
- David Starr Jordan (1851–1931), ichthyologist, 1st president of Stanford
- Félix Pierre Jousseaume (1835–1921), French zoologist and malacologist
- Mike Joy (born 1959), New Zealand freshwater ecologist and science communicator
- Adrien-Henri de Jussieu (1797–1853), French botanist
- Antoine de Jussieu (1686–1758), French naturalist
- Antoine Laurent de Jussieu (1748–1836), botanist, biologist (abbr. in botany: Juss.)
- Bernard de Jussieu (1699–1777), French naturalist
- Ernest Everett Just (1883–1941), American biologist
- Zbigniew Kabata (1924–2014), Polish parasitologist
- Pehr Kalm (1716–1779), Swedish botanist
- Eric R. Kandel (born 1929), Austrian-born American neuroscientist. Winner of the 2000 Nobel Prize in Physiology or Medicine for his work on the neural correlates of memory
- Ferdinand Karsch (1853–1936), German arachnologist, entomologist, and anthropologist
- Gustav Karl Wilhelm Hermann Karsten (1817–1908), German botanist
- Rudolf Kaufmann (1909–c1941), trilobitologist known for his contributions to allopatric speciation and punctuated equilibrium.
- Stuart Kauffman (born 1939), biologist widely known for his promotion of self-organization as a factor in producing the complexity of biological systems and organisms
- Johann Jakob Kaup (1803–1873), German naturalist
- Janet Kear (1933–2004), English ornithologist
- Gerald A. Kerkut (1927–2004), British zoologist and physiologist
- Anton Kerner von Marilaun (1831–1898), Austrian botanist
- Robert Kerr (1755–1813), published The Animal Kingdom in 1792
- Warwick Estevam Kerr (born 1922), Brazilian geneticist, specialist in bee genetics, introducer of African bees in Brazil
- Zofia Kielan-Jaworowska (born 1925), Polish paleontologist, led several paleontological expeditions to the Gobi desert
- Motoo Kimura (1924–1994), Japanese mathematical biologist, working in the field of theoretical population genetics
- Carolyn King, New Zealand zoologist, professor at the University of Waikato, specialising in mammals, particularly small rodents and mustelids
- Norman Boyd Kinnear (1882–1957), Scottish zoologist
- William Kirby (1759–1850), English entomologist
- Heinrich von Kittlitz (1799–1874), German naturalist
- Wilhelm Kobelt (1840–1916), German zoologist and malacologist
- Fritz Köberle (1910–1983), Austrian-Brazilian physician and pathologist, student of Chagas disease
- Karl Koch (1809–1879), German botanist
- Robert Koch (1843–1910), German Nobel Prize-winning physician and bacteriologist
- Emil Theodor Kocher (1841–1917), German physician, winner of the 1909 Nobel Prize in Physiology or Medicine for "his work on the physiology, pathology and surgery of the thyroid gland"
- Alexander Koenig (1858–1940), German naturalist
- Albert von Kölliker (1817–1905), Swiss physiologist
- Charles Konig (1774–1851), German naturalist
- Arthur Kornberg (1918–2007), discovered DNA polymerase
- Adriaan Kortlandt, (born 1918), Dutch ethologist
- Albrecht Kossel (1853–1927), German physician and winner of the 1910 Nobel Prize in Physiology or Medicine for his research in cell biology
- Hans Adolf Krebs (1900–1981), German biochemist and winner of the 1953 Nobel Prize in Physiology or Medicine for his discovery of the citric acid cycle in cellular respiration
- Gerard Krefft (1830–1881), German-born Australian zoologist and palaeontologist
- Eduardo Krieger (born 1930), Brazilian physician and physiologist
- Kewal Krishan (born 1973), Biological Anthropologist, specialized in Forensic Anthropology, serving at Panjab University, Chandigarh, India
- Schack August Steenberg Krogh (1874–1949), Danish physiologist, winner of the 1920 Nobel Prize in Physiology or Medicine for the discovery of the mechanism of regulation of the capillaries in skeletal muscle
- Heinrich Kuhl (1797–1821), German zoologist
- Henri Laborit (1914–1995), French surgeon and physiologist
- Bernard Germain Étienne de la Ville, Comte de Lacépède (1756–1825), French naturalist
- David Lack (1910–1973), British ornithologist
- Frédéric de Lafresnaye (1783–1861), French ornithologist
- Jean-Baptiste Lamarck (1744–1829), French evolutionist, coined many terms like biology and fossils
- Aylmer Bourke Lambert (1761–1842), British botanist
- Charles Lamberton (fl. 1912–1956), French paleontologist
- Hugh Lamprey (1928–1996), British ecologist
- Kai Larsen (1926–2012), Danish botanist
- Charles Francis Laseron (1887–1959), American-born Australian naturalist and malacologist
- John Latham (1740–1837), English naturalist
- Pierre André Latreille (1762–1833), French entomologist
- Charles Louis Alphonse Laveran (1845–1922), French physician, winner of the 1907 Nobel Prize in Physiology or Medicine for his discovery that the cause of malaria is a protozoon
- George Newbold Lawrence (1806–1855), American ornithologist
- William Elford Leach (1790–1836), English zoologist and marine biologist
- Colin Leakey (born 1933), British tropical botanist and specialist in bean science
- Joseph LeConte (1823–1901), physiologist
- Tim Lee (born 1977), comedian
- Antoni van Leeuwenhoek (1632–1723), Dutch biologist, developer of the microscope
- François Leguat (c. 1637 – 1735), French naturalist
- Joseph Leidy (1823–1891), American paleontologist
- Johann Philipp Achilles Leisler (1771–1813), Dutch naturalist
- Juan Lembeye (1816–1889), Spanish naturalist
- Leonardo da Vinci (1452–1519), known as an artist but also an anatomist. Dissected hundreds of specimens and drew exact copies of them
- Jean Baptiste Leschenault de la Tour (1773–1826), French botanist
- Rene Primevere Lesson (1794–1849), French naturalist
- Charles Alexandre Lesueur (1778–1846), French naturalist
- François Le Vaillant (1753–1824), French ornithologist
- Edward B. Lewis (1918–2004), American geneticist and 1995 Nobel Prize-winner
- Richard Lewontin (born 1929), biologist
- Wen-Hsiung Li, Taiwanese molecular evolutionary biologist
- Emmanuel Liais (1826–1900), French botanist
- Martin Lichtenstein (1780–1867), German zoologist
- John Lightfoot (1735–1788), English conchologist and botanist
- David R. Lindberg, American malacologist and biologist
- Aristid Lindenmayer (1925–1989), Hungarian biologist
- John Lindley (1799–1865), English botanist
- Heinrich Friedrich Link (1767–1850), German botanist (abbr. in botany: Link)
- Carl Linnaeus (1707–1778), Swedish botanist; father of the binomial nomenclature system (abbr L. or Linn.)
- Jacques Loeb (1859–1924), German-American biologist
- Friedrich Loeffler (1852–1915), German biologist
- Konrad Lorenz (1903–1989), Austrian founder of ethology
- Harri Lorenzi (born 1949), Brazilian botanist
- John Claudius Loudon (1783–1843), English botanist
- James Lovelock (born 1919), English chemist and father of the Gaia hypothesis
- Percy Lowe (1870–1948), English ornithologist
- Peter Wilhelm Lund (1801–1880), Danish zoologist and paleontologist
- Salvador Luria (1912–1991), microbiologist, Nobel prize winner
- Adolfo Lutz (1855–1940), Brazilian infectologist, pathologist and public health researcher
- André Lwoff (1902–1994), French microbiologist, winner of the 1965 Nobel Prize in Physiology or Medicine
- Richard Lydekker (1849–1915), English naturalist
- Trofim Lysenko (1898–1976), Soviet biologist and agronomist. His denouncement of genetics became known as Lysenkoism.
Ma-Mi
- Jules François Mabille (1831–1904), French malacologist
- John Macadam (1827–1865), Scottish-born Australian botanist
- John M. MacDougal (born 1954), American botanist
- William MacGillivray (1796–1852), Scottish naturalist
- Eileen McLaughlin NZ biologist
- Marcello Malpighi (1628–1694), Italian anatomist and biologist
- Ramon Margalef (1919–2004), Spanish-Catalan biologist and ecologist
- Leo Margolis (1927–1997), Canadian fisheries parasitologist
- Lynn Margulis (born 1938), American microbiologist
- Alberto della Marmora (1789–1863), Italian naturalist
- Othniel Charles Marsh (1831–1899), paleontology
- Barry Marshall (born 1951), Australian physician and microbiologist, winner of the 2005 Nobel Prize in Physiology or Medicine for his discovery that most stomach ulcers are caused by a strain of bacteria
- Bruce Marshall (born 1948), New Zealand malacologist
- Fermín Martín Piera (1954–2001), Spanish botanist
- Carl Friedrich Philipp von Martius (1794–1868), German botanist
- John Martyn (1699–1768), English botanist
- Thomas Martyn (1735–1825), English botanist, entomologist and conchologist
- John Marwick (1891–1978), New Zealand palaeontologist and geologist
- Teresa Maryańska, Poland, paleontologist specializing in dinosaurs
- Ruth Mason (1913-1990), New Zealand botanist
- Francis Masson (1741 – c. 1805), Scottish botanist
- Gregory Mathews (1876–1949), Australian ornithologist
- Paul Matschie (1861–1926), German zoologist
- William Diller Matthew (1871–1930), American paleontologist
- Polly Matzinger, American immunologist
- Carl Maximowicz (1827–1891), Russian botanist
- Harold Maxwell-Lefroy (1877–1925), English entomologist
- Robert May (born 1936), biologist, physicist, mathematician, President of Royal Society of London 2000–2005
- Ernst Mayr (1904–2005), evolutionary biologist
- Barbara McClintock (1902–1992), American biologist, winner of a Nobel Prize for her work on the transposon, or "jumping gene"
- James V. McConnell (1925–1990), American biological psychologist
- Mark McMenamin (born 1958), American paleontologist
- Bruce McEwen, neuroendocrinologist and stress hormone expert
- Edmund Meade-Waldo (1855–1934), English ornithologist
- Ilya Ilyich Mechnikov (1845–1916), Russian microbiologist, best known for his work on the immune system and phagocytosis, received the Nobel Prize in Physiology or Medicine in 1908
- Johann Wilhelm Meigen (1764–1845), German entomologist
- Gregor Mendel (1822–1884), Czech-Austrian monk who is often called the "father of genetics" for his study of the inheritance of traits in pea plants
- Edouard Menetries (1802–1861), French entomologist
- Maud Leonora Menten, biologist
- Archibald Menzies (1754–1852), Scottish naturalist
- Clinton Hart Merriam (1855–1942), American zoologist and ornithologist
- John C. Merriam (1869–1945), American biologist
- Don Merton (1939-2011), New Zealand conservationist
- Franz Meyen (1804–1840), German botanist
- Rodolphe Meyer de Schauensee (1901–1984), American ornithologist
- Otto Fritz Meyerhof (1884–1951), German/American physician and biochemist, winner of the 1922 Nobel Prize in Physiology or Medicine for his research on muscles
- Leonor Michaelis (1875–1949), German biologist
- André Michaux (1746–1802), French botanist
- Aleksandr Fyodorovich Middendorf (1815–1894), Russian zoologist
- Nicholai Miklukho-Maklai (1846–1888), Russian marine biologist and anthropologist
- Gerrit Smith Miller, Jr. (1869–1956), American zoologist.
- Jacques Miller (born 1931), Australian immunologist.
- John Frederick Miller (1759–1796), English illustrator (primarily of botany)
- Kenneth R. Miller (born 1948), American evolutionary biologist.
- Philip Miller (1691–1771), Scottish botanist (abbr. in botany: Mill.)
- Alphonse Milne-Edwards (1835–1900), French zoologist
- Henri Milne-Edwards (1800–1885), French zoologist
- George Jackson Mivart (1827–1900), English biologist
Mo-Mu
- Hugo von Mohl (1805–1872), German botanist
- Paul Möhring (1710–1792), German naturalist
- Juan Ignacio Molina (1740–1829), Chilean naturalist
- Brian Molloy (born 1930), New Zealand botanist
- Pérrine Moncrieff (1893-1979), New Zealand ornithologist
- Jacques Monod (1910–1976), geneticist
- George Montagu (1753–1815), English naturalist
- Luc Montagnier (born 1932), French discoverer of HIV
- Rita Levi-Montalcini (born 1909), Italian-American neurologist who received the 1986 Nobel Prize in Physiology or Medicine for her co-discovery of growth factors
- Tommaso di Maria Allery Monterosato (1841–1927), Italian malacologist
- Pierre Dénys de Montfort (1766–1820), French naturalist
- George Thomas Moore (1871–1956), American botanist
- Alfred Moquin-Tandon (1804–1863), French naturalist
- Otto Andreas Lowson Mörch (1828–1878), malacologist
- Thomas Hunt Morgan (1868–1945), American geneticist. He worked on the natural history, zoology, and macromutation in the fruit fly Drosophila
- Mary Morgan-Richards, New Zealand evolutionary biologist
- Desmond Morris (born 1928), British zoologist and biologist
- Roger Morse (1927–2000), professor, researcher, author, on bees/beekeeping
- Guy Mountfort (1905–2003), English ornithologist
- Ladislav Mucina (born 1956), Slovakian botanist
- Ferdinand von Mueller (1825–1896), German-Australian botanist
- John Muir (1838–1914), American naturalist
- Otto Friedrich Müller (1730–1784), Danish naturalist (abbr. in botany: O.F.Müll.)
- Fritz Müller (1821–1897), German-Brazilian naturalist (abbr. in botany: F.J.Müll.)
- Hermann Müller (Thurgau) (1850–1927), Swiss botanist and oenologist
- Philipp Ludwig Statius Müller (1725–1776), German zoologist
- Salomon Muller (1804–1864), Dutch naturalist
- Kary Mullis (born 1944), biologist
- Otto von Münchhausen (1716–1774), German botanist
- John Murray (1841–1914), Scots-Canadian Marine Biologist
- Gary Paul Nabhan (born 1952), co-author of Forgotten Pollinators
- Karl Wilhelm von Nageli (1817–1891), Swiss botanist
- Johann Friedrich Naumann (1780–1857), German founder of scientific ornithology
- John Needham (1713–1781), English naturalist
- Christian Gottfried Daniel Nees von Esenbeck (1776–1858), German botanist and zoologist
- Masatoshi Nei, American evolutionary biologist and molecular Population Geneticist
- Wendy Nelson New Zealand phycologist
- Randolph M. Nesse (born 1945), American evolutionary biologist and psychiatrist
- Charles F. Newcombe (1851–1924), British botanist
- Frank Newhook (1918-1999), New Zealand plant pathologist
- Alfred Newton (1829–1907), English zoologist
- Margaret Morse Nice (1883–1974), American ornithologist
- Henry Alleyne Nicholson (1844–1899), British zoologist
- Elmer Noble (1909–2001), American parasitologist
- Alfred Merle Norman (1831–1918), English clergyman and naturalist
- Alfred John North (1855–1917), Australian ornithologist
- Christiane Nüsslein-Volhard (born 1942), German biologist and 1995 Nobel Prize-winner
- Thomas Nuttall (1786–1858), English botanist and zoologist
- Nils Hjalmar Odhner (1884–1973), Swedish zoologist
- Eugene P. Odum (1913–2002), American ecologist
- Howard T. Odum (1924–2002), American ecologist
- Anders Sandoe Oersted (1816–1872), Danish botanist (abbr. in botany: Oerst.)
- William Ogilby (1808–1873), Irish naturalist
- William Robert Ogilvie-Grant (1863–1924), Scottish ornithologist
- Sergey Ognev (1886–1951), Russian zoologist
- Tomoko Ohta (born 1933), Japanese molecular evolutionary biologist
- Lorenz Oken (1779–1851), German naturalist
- Giuseppe Olivi (1769–1795), Italian naturalist
- Mark A. O'Neill, British biologist and computer scientist
- Aleksandr Oparin (1894–1980), Russian biologist and biochemist, best known for his work on the origin of life
- Alcide d'Orbigny (1802–1857), French naturalist
- George Ord (1781–1866), American ornithologist
- Eleanor Anne Ormerod (1828–1901), English entomologist
- Edward Latham Ormerod (1819–1873), FRS, English physician and entomologist
- Henry Fairfield Osborn (1857–1935), eugenicist, AMNH curator
- William Charles Osman Hill (1901–1975), British anatomist, primatologist, and a leading authority on primate anatomy during the 20th century
- Halszka Osmólska (1930–2008), Polish paleontologist specializing in dinosaurs
- Emile Oustalet (1844–1905), French zoologist
- Richard Owen (1804–1892), biologist of nebres(triztan) organisms
- George Emil Palade (born 1912), Romanian-American biologist, discoverer of ribosomes, Nobel Prize
- Paul Maurice Pallary (1869–1942), French-Algerian malacologist
- Peter Simon Pallas (1741–1811), Russian zoologist
- Edward Palmer (1829–1911), British botanist
- Josif Pancic (1814–1888), Serbian botanist
- Paracelsus (1493–1541), German alchemist
- Louis Pasteur (1822–1895), French biochemist
- William Paterson (1755–1810), British botanist and explorer
- Robert Patterson (1802–1872), Irish naturalist
- Daniel Pauly (born 1946), French marine biologist
- Ivan Pavlov (1849–1936), Russian physiologist, psychologist and physician, discovered conditioning, won the Nobel Prize for his research on the digestive system
- Titian Peale (1799–1885), American naturalist
- Louise Pearce (1885–1959), American pathologist
- Donald C. Peattie (1898–1964), American botanist
- Eva J. Pell (born 1948), American plant pathologist
- Paul Pelseneer (1863–1945), Belgian malacologist
- Jean-Marie Pelt (born 1933), French botanist
- Thomas Pennant (1726–1798), Welsh naturalist and antiquary
- David Penny (born 1939), New Zealand evolutionary biologist and geneticist
- Henri Perrier de la Bâthie (1873–1958), French botanist
- George Perry (naturalist), 19th century English naturalist
- Christian Hendrik Persoon (1761–1836), biologist
- Paul Petard (1912–1980), French botanist
- Wilhelm Peters (1815–1883), German naturalist
- Ludwig Karl Georg Pfeiffer, German physician, botanist and conchologist
- Rodolfo Amando Philippi (1808–1904), German-Chilean zoologist
- Constantine John Phipps (1744–1792), English explorer
- David Andrew Phoenix, (born 1966), Biochemist
- Frederick Octavius Pickard-Cambridge (1860–?), English entomologist
- Octavius Pickard-Cambridge (1828–1917), English entomologist, uncle of above
- Charles Pickering (1805–1878), American naturalist
- Cándido Bolívar Pieltain (1897–1976), Spanish naturalist
- Henry Augustus Pilsbry (1862–1957), American zoologist, malacologist
- Gregory Goodwin Pincus (1903–1967), American biologist and co-inventor of the contraceptive pill
- Ronald Plasterk, (born 1957), Dutch molecular biologist, columnist and politician
- Pliny the Elder (23–79), Roman natural philosopher
- Reginald Innes Pocock (1863–1947), British taxonomist (mammals and arachnids)
- Felipe Poey (1799–1891), Cuban zoologist
- Joel Roberts Poinsett (1779–1851), American botanist
- Henry de Puyjalon (1841–1905), Canadian ecologist and biologist
- Giuseppe Saverio Poli (1746–1825), Italian physicist, biologist and natural historian
- Winston Ponder (born 1941), New Zealand malacologist
- Arthur William Baden Powell (1901–1987), New Zealand malacologist and paleontologist
- Thomas Littleton Powys, 4th Baron Lilford (1833–1896), English ornithologist
- Karel Presl (1794–1852), Bohemian botanist
- Alice Pruvot-Fol (1873–1972), French malacologist
- Jan Evangelista Purkyně (1787–1869), Czech anatomist and physiologist
- Frederick Traugott Pursh (1774–1820), German-American botanist
- Paul Émile de Puydt (1810–1888), Belgian botanist
- Nikolai Przhevalsky (1839–1888), Russian explorer
- Jean Louis Armand de Quatrefages de Bréau (1810–1892), French naturalist
- Jean René Constant Quoy (1790–1869), French zoologist
- Gustav Radde (1831–1903), German naturalist
- Thomas Stamford Raffles (1781–1826), British founder/first president of the Zoological Society of London
- Constantine Samuel Rafinesque (1783–1840), French naturalist who described many North American species
- Émile Louis Ragonot (1843–1895), French entomologist
- Santiago Ramón y Cajal (1852–1934), Spanish histologist and Nobel laureate. Considered the father of neuroscience.
- Edward Pierson Ramsay (1842–1916), Australian ornithologist
- Austin L. Rand (1905–1982), Canadian zoologist
- Suresh Rattan (born 1955), Indian biogerontologist
- John Ray (1627–1705), English naturalist
- Francesco Redi (1626–1697), Italian physician known for his experiment in 1668 which is regarded as one of the first steps in refuting abiogenesis
- Lovell Augustus Reeve (1814–1865), English conchologist
- Heinrich Gustav Reichenbach (1823–1889), German orchidologist (abbr. in botany: Rchb. f.)
- Ludwig Reichenbach (1793–1879), German botanist and ornithologist (abbr. in botany: Rchb.)
- Anton Reichenow (1847–1941), German ornithologist
- Caspar Georg Carl Reinwardt (1773–1854), Dutch botanist
- Bernhard Rensch (1900–1990), German biologist
- Ralf Reski (born 1958), German botanist and biotechnologist, developed Physcomitrella as model organism
- Achille Richard (1794–1852), French botanist (abbr. in botany: A. Rich)
- Jean Michel Claude Richard (1787–1868), noted French botanist and plant collector (abbr. in botany: J.M.C.Rich.)
- Louis Claude Richard (1754–1821), French botanist (abbr. in botany: Rich.)
- Olivier Jules Richard (1836–1896), French lichenologist (abbr. in botany: O.J.Rich.)
- John Richardson (1787–1865), Scottish naturalist (abbr. in botany: Richardson)
- Charles Richet (1850–1935), French physiologist, winner of the 1913 Nobel Prize for Physiology or Medicine for his discovery of anaphylaxis
- Charles Wallace Richmond (1868–1932), American ornithologist
- Robert Ridgway (1850–1929), American ornithologist
- Henry Nicholas Ridley (1855–1956), British botanist (abbr. in botany: Ridl.)
- Christina Riesselman American paleoceanographer
- Austin Roberts (1883–1948), South African zoologist
- Harold E. Robinson (born 1932), American botanist and entomologist
- Maurício Rocha e Silva (1910–1983), Brazilian physician and pharmacologist, codiscoverer of bradykinin
- Martin Rodbell (1925–1998), biologist
- Peter Friedrich Röding (1767–1846), German malacologist
- George Romanes (1848–1894), Canadian naturalist, founded the discipline of comparative psychology
- Alfred Romer (1894–1973), specialist in vertebrate paleontology
- Robert Rosen (1934–1998), theoretical biologist
- Joel Rosenbaum (born 1933), cell biologist at Yale University
- Harald Rosenthal (born 1937), German hydrobiologist known for his work in fish farming and ecology
- Miriam Louisa Rothschild (1908–2005), British entomologist
- Walter Rothschild, 2nd Baron Rothschild (1868–1937), British zoologist
- Joan Roughgarden (born 1946), American ecologist and evolutionary biologist
- William Roxburgh (1759–1815), Scottish botanist
- Adriaan van Royen (1704–1779), Dutch botanist (abbr. in botany: Royen)
- Karl Rudolphi (1771–1832), German physiologist
- Eduard Rüppell (1794–1884), German naturalist
Sa-So
- Joseph Sabine (1770–1837), English naturalist
- Julius von Sachs (1832–1897), German botanist
- Étienne Geoffroy Saint-Hilaire (1772–1844), French naturalist
- Isidore Geoffroy Saint-Hilaire (1805–1861), French zoologist
- Carl Ulisses von Salis-Marschlins (1762–1818), Swiss naturalist interested in botany, entomology, and conchology
- Edward James Salisbury (1886–1978), British botanist
- Richard Anthony Salisbury (1761–1829), British botanist
- Jonas Salk (1914–1995), American biologist, inventor of polio vaccine
- Robert Sapolsky (born 1957), American neuroscientist
- Georg Ossian Sars (1837–1927), Norwegian marine biologist
- Michael Sars (1809–1869), Norwegian taxonomist
- Konstantin Satunin (1863–1915), Russian zoologist
- William Saunders (1822–1900), American botanist
- Horace-Bénédict de Saussure (1740–1799), Swiss naturalist
- Marie Jules César Savigny (1777–1851), French zoologist
- Thomas Say (1787–1843), American naturalist
- George Schaller (born 1933), American zoologist, widely considered the preeminent field biologist of the 20th century
- Friedrich Schlechter (1872–1925), German botanist
- Hermann Schlegel (1804–1884), German ornithologist
- Matthias Jakob Schleiden (1804–1881), German co-founder of the cell theory
- George Schoener (1864–1941), German-American botanist
- Johann David Schoepf (1752–1800), German botanist and zoologist
- Heinrich Wilhelm Schott (1794–1865), German botanist
- Johann Christian Daniel von Schreber (1739–1810), German naturalist
- Leopold von Schrenck (1826–1894), Russo-German zoologist
- Charles Schuchert (1858–1942), paleontologist
- Theodor Schwann (1810–1882), German physiologist
- Neena Schwartz (born 1926), American endocrinologist
- Georg August Schweinfurth (1836–1925), German botanist
- Philip Sclater (1829–1913), English zoologist
- Giovanni Antonio Scopoli (1723–1788), Italian-Austrian naturalist
- Henry Seebohm (1832–1895), English ornithologist
- Prideaux John Selby (1788–1867), English botanist and ornithologist
- Nikolai Alekseevich Severtzov (1827–1885), Russian naturalist
- Richard Bowdler Sharpe (1847–1909), English zoologist
- George Shaw (1751–1813), English botanist and zoologist
- George Ernest Shelley (1840–1910), English ornithologist
- Sir Charles Scott Sherrington (1857–1922), British physiologist and neuroscientist, winner of the 1932 Nobel Prize in Physiology or Medicine for his research on neurons
- Philipp Franz von Siebold (1796–1866), German botanist
- George Gaylord Simpson (1902–1984), American paleontologist
- Rolf Singer (1906–1994), German born mycologist
- Liz Slooten New Zealand zoologist
- John Kunkel Small (1869–1938), American botanist (abbr. in botany: Small)
- Andrew Smith (1797–1872), Scottish zoologist
- Edgar Albert Smith (1847–1916), British zoologist and conchologist
- Frederick Smith (1805–1879), British entomologist
- James Edward Smith (1759–1828), English botanist (abbr. in botany: Sm.)
- Johannes Jacobus Smith (1867–1947), Dutch botanist (abbr. in botany: J.J.Sm.)
- James Leonard Brierley Smith (1897–1968), South African ichthyologist
- John Maynard Smith (1920–2004), biologist
- John Otterbein Snyder (1867–1943), American zoologist
- Solomon H. Snyder (born 1938), American neuroscientist, co-discovered endorphins
- Daniel Solander (1733–1782), Swedish botanist
- Louis François Auguste Souleyet (1811–1852), French zoologist
Sp-Sy
- Douglas Spalding (c1840–1877), English biologist, discovered imprinting and conducted some of the earliest research on animal behavior
- Lazzaro Spallanzani (1729–1799), Italian biologist
- Anders Sparrman (1748–1820), Swedish naturalist
- Walter Baldwin Spencer (1860–1929), English biologist and anthropologist
- Roger W. Sperry (1913–1994), American neuropsychologist, winner of the 1981 Nobel Prize in Physiology or Medicine for his split-brain research
- Maximilian Spinola (1780–1857), entomologist
- Johann Baptist von Spix (1781–1826), German naturalist
- Herman Spoering (1733–1771), Finnish botanist
- Kurt Sprengel (1766–1833), German botanist
- Stewart Springer (1906–1991), American ichthyologist noted for expertise in shark classification, behavior, and distribution of species
- Richard Spruce (1817–1893), English botanist
- Agustin Stahl (1842–1917), Puerto Rican zoologist and botanist
- Edward Stanley, 13th Earl of Derby (1775–1851), English naturalist
- Japetus Steenstrup (1813–1897), Danish zoologist
- Franz Steindachner (1834–1919), Austrian zoologist
- Leonhard Hess Stejneger (1851–1943), Norwegian zoologist
- Georg Wilhelm Steller (1709–1746), Russian ornithologist
- James Francis Stephens (1792–1853), English zoologist
- Kaspar Maria von Sternberg (1761–1838), Bohemian botanist
- Karl Stetter (born 1941), German microbiologist
- Nettie Maria Stevens (1861–1912), American biologist
- Edward Charles Stirling (1848–1919), Australian anthropologist
- Gerald Stokell (1890–1972), New Zealand horticulturist and ichthyologist
- Witmer Stone (1866–1939), American ornithologist, botanist, and mammalogist
- Gottlieb Conrad Christian Storr (1749–1821), German naturalist
- Vida Stout (1930-2012), New Zealand limnologist
- Eduard Strasburger (1844–1912), German botanist (abbr. in botany: Strasb.)
- Erwin Stresemann (1889–1972), German ornithologist
- John Struthers (1823–1899), Scottish anatomist
- Samuel Stutchbury (1798–1859), English naturalist and geologist
- Richard Summerbell (born 1956), Canadian mycologist
- Carl Jakob Sundevall (1801–1875), Swedish zoologist
- Mriganka Sur (born 1953), Indian cognitive neuroscientist specializing in neuroplasticity
- Henry Suter (1841–1918), New Zealand zoologist, naturalist and palaeontologist
- Mary Sutherland (1893-1955), New Zealand botanist
- William John Swainson (1789–1855), English ornithologist, malacologist, conchologist, entomologist and artist
- Jan Swammerdam (1637–1680), Dutch biologist and microscopist
- Olof Swartz (1760–1816), Swedish botanist (abbr. in botany: Sw.)
- Robert Swinhoe (1836–1877), English naturalist
- Colonel W. H. Sykes (1790–1872), English ornithologist
- Wladyslaw Taczanowski (1819–1890), Polish zoologist
- Armen Takhtajan (born 1910), Russian botanist
- Diana Temple (1925-2006), Australian pharmacologist
- Peter Gustaf Tengmalm (1754–1803), Swedish naturalist
- Coenraad Jacob Temminck (1778–1858), Dutch zoologist
- Theophrastus (372 BC – 287 BC), biologist and the successor of Aristotle in the Peripatetic school, popularizer of science
- Johannes Thiele (1860–1935), German zoologist and malacologist
- Michael Rogers Oldfield Thomas (1858–1929), British zoologist
- Charles Wyville Thompson (1832–1882), Scottish marine biologist
- William Thompson (1805–1852), Irish ornithologist and naturalist
- Louis-Marie Aubert du Petit-Thouars (1758–1831), French botanist
- Carl Peter Thunberg (1743–1828), Swedish naturalist
- Samuel Tickell (1811–1875), British ornithologist
- Niko Tinbergen (1907–1988), Dutch ethologist
- Agostino Todaro (1818–1892), Italian botanist
- Susumu Tonegawa (born 1939), Japanese biologist, winner of the 1987 Nobel Prize in Physiology or Medicine for "discovery of the genetic principle for generation of antibody diversity"
- John Torrey (1796–1873), American botanist, first professional in New World
- Joseph Pitton de Tournefort (1656–1708), French botanist
- John Kirk Townsend (1809–1851), American ornithologist
- Thomas Stewart Traill (1781–1862), Scottish doctor and naturalist
- Abraham Trembley (1710–1784), Swiss naturalist
- Melchior Treub (1851–1910), Dutch botanist
- Henry Baker Tristram (1822–1906), English ornithologist
- Robert Trivers (born 1943), evolutionary biologist
- Édouard Louis Trouessart (1842–1927), French naturalist
- Frederick W. True (1858–1914), American naturalist
- George Washington Tryon Jr. (1838–1888), American malacologist
- Bernard Tucker (1901–1950), English ornithologist
- Edward Tuckerman (1817–1886), American botanist
- Endel Tulving (born 1927), Estonian-born Canadian neuroscientist, specializes in episodic memory
- Marmaduke Tunstall (1743–1790), English ornithologist
- Ruth Turner (1915–2000), marine biologist
- William Turton (1762–1835), British naturalist
- Jakob von Uexküll (1864–1944), Estonian biologist, founder of biosemiotics
- Martin Vahl (1749–1804), Norwegian botanist
- Sebastien Vaillant (1669–1722), French botanist
- Achille Valenciennes (1794–1865), French zoologist
- Francisco Varela (1946–2001), Chilean biologist
- Nikolai Vavilov (1887–1943), Soviet botanist and geneticist, died in prison as a defender of "bourgeois pseudoscience" genetics against Lysenkoism
- Damodaran M. Vasudevan (born 1942), Indian physician, immunologist and educationist
- Craig Venter (born 1946), American biologist and businessman
- Edouard Verreaux (1810–1868), French naturalist
- Jules Verreaux (1807–1873), French botanist and ornithologist
- Addison Emery Verrill (1839–1926), American zoologist
- Louis Jean Pierre Vieillot (1748–1831), French ornithologist
- Nicholas Aylward Vigors (1785–1840), Irish zoologist
- Rudolf Virchow (1821–1902), German biologist and pathologist, founder of cell theory
- Oswaldo Vital Brazil (1865–1950), Brazilian physician and immunobiologist, discoverer of several antivenoms against snake, scorpion and spider bites
- Bert Vogelstein (born 1949), American geneticist
- Karel Voous (1920–2002), Dutch ornithologist
- Mary Voytek, American biogeochemist and microbial ecologist
- Hugo de Vries (1848–1935), Dutch botanist
- Frans de Waal (born 1948), Dutch ethologist, primatologist and psychologist
- Coslett Herbert Waddell (1858–1919), Irish botanist
- Jeremy Wade (born 1960) Writer and TV presenter with a special interest in rivers and freshwater fish.
- Amy Wagers, biologist, stem cell and regenerative biology
- Johann Georg Wagler (1800–1832), German herpetologist
- Warren H. Wagner (1920–2000), American botanist
- Göran Wahlenberg (1780–1851), Swedish naturalist
- Selman Waksman (1888–1973), American biochemist, winner of the 1952 Nobel Prize in Physiology or Medicine for his work on antibiotics
- Charles Athanase Walckenaer (1771–1852), French entomologist
- George Wald (1906–1997), American biologist, winner of the 1967 Nobel Prize in Physiology or Medicine for his work on visual perception
- Alfred Russel Wallace (1823–1913), British naturalist and biologist
- Nathaniel Wallich (1786–1854), Danish botanist
- Benjamin Dann Walsh (1808–1869), American entomologist
- William Grey Walter (1910–1977), American neurophysiologist and roboticist, made a number of important discoveries in the field of electroencephalography
- Deepal Warakagoda (born 1965), Sri Lankan ornithologist
- J. Robin Warren (born 1937), Australian pathologist, winner of the 2005 Nobel Prize in Physiology or Medicine for his discovery that most stomach ulcers are caused by a strain of bacteria
- Charles Waterton (1782–1865), English naturalist
- James D. Watson (born 1928), Nobel Prize-winning biologist, co-discoverer of the structure of the DNA molecule
- Philip Barker Webb (1793–1854), English botanist (abbr. in botany: Webb)
- Hugh Algernon Weddell (1819–1877), English botanist (abbr. in botany: Wedd.)
- Robert Weinberg (born 1942), American cancer biologist
- August Weismann (1834–1914), German biologist
- Friedrich Welwitsch (1806–1872), Austrian botanist
- Karl Wernicke (1848–1905), German physician and neuroanatomist, discovered Wernicke's area
- Victor Westhoff (1916–2001), Dutch botanist
- Alexander Wetmore (1886–1978), American ornithologist
- William Morton Wheeler (1865–1937), American entomologist and myrmecologist
- Gilbert White (1720–1795), English naturalist
- John White (c. 1756–1832), English botanist
- Robert Wiedersheim (1848–1923), German anatomist.
- Prince Alexander Philipp Maximilian zu Wied-Neuwied (1782–1867), German explorer and biologist.
- Hans Wiehler (1930–2003), American botanist (abbr. in botany: Wiehler)
- Eric F. Wieschaus (born 1947), American developmental biologist and 1995 Nobel Prize-winner
- Torsten Wiesel (born 1924), Swedish-born American neurobiologist, winner of the 1981 Nobel Prize in Physiology or Medicine for his research on information processing in the visual system
- Joan Wiffen (1922-2009), New Zealand paleontologist
- Siouxsie Wiles, New Zealand microbiologist
- Charles Wilkes (1798–1877), American explorer and naturalist
- Carl Ludwig Willdenow (1765–1812), German botanist and pharmacist (abbr. in botany: Willd.)
- George C. Williams (born 1926), American evolutionary biologist, credited with introducing the gene-centric view of evolution
- Mark Williamson, British biologist
- Francis Willughby (1635–1672), English ornithologist and ichthyologist
- Alexander Wilson (1766–1813), Scottish-American ornithologist
- David Sloan Wilson (born 1949), American evolutionary biologist
- E. A. Wilson (1872–1912), English naturalist
- Edward O. Wilson (born 1929), American entomologist and father of sociobiology, two-time winner of the Pulitzer Prize
- Sergei Winogradsky (1856–1953), Russian microbiologist, ecologist and soil scientist who pioneered the cycle of life concept and discovered the biological process of nitrification
- Caspar Wistar (1761–1818), American anatomist and physician. The genus Wisteria is named after him
- Henry Witherby (1873–1943), British ornithologist
- William Withering (1741–1799), English botanist
- Carl Woese (1928–2012), American microbiologist, identified the Archaea, a major division of organisms
- Felisa Wolfe-Simon, American biogeochemist and microbial geobiologist
- Wong Siew Te (born 1969), Malaysian zoologist and Sun Bear expert
- Flossie Wong-Staal (born 1947), American virologist
- Sewall Wright (1889–1988), American geneticist, co-founder of population genetics
- V. C. Wynne-Edwards (1906–1997), Scottish zoologist, introduced the hypothesis of group selection in evolution
- John Xantus de Vesey (1825–1894), American zoologist
- William Yarrell (1784–1856), English naturalist
- Floyd Zaiger (born 1926), fruit geneticist
- Eberhard August Wilhelm von Zimmermann (1743–1815), German zoologist
- Karl Alfred von Zittel (1839–1904), German palaeontologist
- Joseph Gerhard Zuccarini (1797–1848), German botanist
- Margarete Zuelzer (1877–1944), German biologist and zoologist